The practice of sharing syringes without adequate sterilisation between successive users is a major contributor to the transfer of Human Immunodeficiency Virus and Hepatitis with subsequent severe repercussions for the sufferer of such diseases and at a high cost to society of supporting and providing medical attention to those sufferers.
Another significant risk associated with unclean needles and syringes arises from the possibility of inadvertent needle-stick injuries. This is particularly a problem for law enforcement officers and paramedics who often encounter users of illegal drugs in their professional activities. Additionally, the habits of illegal drug users are such that dangerous by-products of their activities, such as discarded syringes, are often left in places of public access presenting a risk to the users of areas such as public parks and school grounds.
Used syringes are also dangerous in hospitals, medical centres and surgeries where needlestick injuries may injure doctors, nurses and other health professionals.
A recent development in syringes has been to design syringes where the needle is permanently retractable into the barrel of the syringe.
For example, International Publication WO 01/80930 describes a single-use retractable syringe that is highly effective in preventing syringe re-use by ensuring full depression of the plunger during fluid delivery and by ensuring permanent withdrawal of the needle by the plunger back into the syringe barrel.
In such cases, retraction is facilitated by a spring, which at the end of injection forces the plunger and needle engaged therewith to retract into the barrel automatically.